We provide a direct experimental proof and the related modeling of the role played by Si overgrowth in promoting the lateral ordering of Ge islands grown by chemical vapor deposition on Si(001). The deposition of silicon induces a shape transformation, from domes to truncated pyramids with a larger base, generating an array of closely spaced interacting islands. By modeling, we show that the resulting gradient in the chemical potential across the island should be the driving force for a selective flow of both Ge and Si atoms at the surface and, in turn, to a real motion of the dots, favoring the lateral order.
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http://dx.doi.org/10.1103/PhysRevLett.96.106102 | DOI Listing |
Nanotechnology
July 2009
Institute of Applied Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions.
View Article and Find Full Text PDFPhys Rev Lett
March 2006
INRS Energie, Matériaux et Télécommunications, Université du Québec, 1650 Boulevard Lionel Boulet, J3X 1S2 Varennes (QC), Canada.
We report a low energy electron microscopy study of the relation between self-organized Ge/Si(111)nanostructures and their local environment. By comparison with Monte Carlo simulations, three-dimensional islands are shown to display a substantial tendency towards self-ordering. This tendency may result from the diffusive nature of the nucleation processes.
View Article and Find Full Text PDFPhys Rev Lett
March 2006
Dipartimento di Fisica E. Amaldi, Università Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy.
We provide a direct experimental proof and the related modeling of the role played by Si overgrowth in promoting the lateral ordering of Ge islands grown by chemical vapor deposition on Si(001). The deposition of silicon induces a shape transformation, from domes to truncated pyramids with a larger base, generating an array of closely spaced interacting islands. By modeling, we show that the resulting gradient in the chemical potential across the island should be the driving force for a selective flow of both Ge and Si atoms at the surface and, in turn, to a real motion of the dots, favoring the lateral order.
View Article and Find Full Text PDFPhys Rev Lett
July 2000
Centre for Nanoscale Science and Technology, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom.
We report the formation of novel mesoscopic two-dimensional bubble structures coexisting with nanometer-scale, two monolayer high, meandering islands of characteristic separation approximately 11 nm on CaF2(111) surfaces exposed to glancing incidence ion beam irradiation (4 degrees, 4.5 keV Ar+). The island and bubble structures can be explained, respectively, by nanoscale stress domain related local self-ordering of a single calcium adlayer on phase-separated F- (fluorine ion) and F-center (color center) terminated mesoscopic domains.
View Article and Find Full Text PDFPhys Rev B Condens Matter
April 1996
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